1. Field of the Disclosure
The present invention relates to techniques for correcting vibration of an image capturing apparatus using an optical image stabilization method and an electrical image stabilization method in the image capturing apparatus.
2. Description of the Related Art
In recent years, image capturing apparatuses have been downsized and optical systems with higher magnification have been employed. The vibration or the like of such an image capturing apparatus is a major cause of degradation in the quality of an image captured by the image capturing apparatus. In view of the circumstances, a variety of blur correction functions have been proposed for correcting a blur of a captured image caused by vibration or the like of such an image capturing apparatus. Examples of conventional blur correction functions incorporated into an image capturing apparatus include a correction method in which both an optical image stabilization method and an electrical image stabilization method are used (see, for example, Japanese Patent Laid-Open No. 11-146260).
First, in the optical image stabilization method, vibration of an image capturing apparatus is detected, and an optical system for image stabilization is driven in order to cancel the detected vibration. The optical system for image stabilization causes light of an object, which enters an image sensor, to be always located at the same position on an imaging plane, thereby correcting vibration. Subsequently, in the electrical image stabilization method, a residual blur, which could not be corrected by the optical image stabilization method, is detected by obtaining a blur between images. Then, by shifting a readout region of the image so that the obtained blur between the images is cancelled, residual vibration in a low frequency is corrected. As such, it is possible to improve correction capability by using the optical image stabilization method and the electrical image stabilization method.
However, the above-described conventional method has the following problem. Optical image stabilization is to correct vibration of an image capturing apparatus by mechanically driving an optical system for image stabilization, where a correction amount is finite. Accordingly, in general, when significant vibration is added to an image capturing apparatus or the image capturing apparatus is panned, the optical image stabilization is controlled so as to achieve a reduced effect of image stabilization, in order to avoid reaching a limit of correction.
In this case, if regular electrical image stabilization is performed, it corrects a residual blur which has been increased due to the reduced effect of image stabilization in the optical image stabilization. In an electrical image stabilization method, a blur during a charge accumulation period cannot be corrected. Therefore, if an image having the increased residual blur is corrected by means of the electrical image stabilization, this will bring about a phenomenon that only a blur during a charge accumulation period is generated while an object is being stopped on a screen. This results in an extremely unnatural image.